Process of electrodepositing nickel and electrolyte and additive composition therefor



United States Patent US. Cl. 20449 13 Claims ABSTRACT OF THE DISCLOSURE Aqueous acid nickel electroplating baths containing as a brightener a compound having a molecular structure which includes one or more units of the formula:

wherein R and R are from the group of oxymethylene and oxyethylene, m and m are each an integer of 01, n and n are each an integer of 1-2, and y is an integer of at least 1.

This invention relates to novel condensation reaction products of a naphthosultone and an acetylenically unsaturated glycol, and more especially to new and improved nickel electroplating baths containing such condensation reaction products, as additives, novel compositions containing the condensation reaction products herein and especially well suited as brightener additives for the baths, and an improved method for electroplating nickel involving the use of the new baths herein. Additionally, this invention relates to the condensation reaction products per se, and a novel method for the preparation of such products.

It is known in the prior art to utilize in nickel electro plating baths unreacted acetylenically unsaturated glycols, such as butynediols. However such glycol additives have the drawback of giving good results only at slow plating speeds. Likewise the addition to the baths of unreacted acetylenically unsaturated sulfonic acids has been proposed for instance by US. Patents 3,002,903 and 3,002,904 and by German Patent 1,017,873. Such baths however do not permit one to obtain bright, thin deposits of nickel.

One object of this invention is to provide new and improved nickel electroplating baths for providing bright nickel deposits.

Another object is to provide novel condensation reaction products of .a naphthasultone, for instance a 1,8-naphthosultone, with an acetylenically unsaturated glycol, eminently well suited as a brightener additive for nickel electroplating baths.

A further object is to provide new compositions containing such new condensation reaction products and especially well suited as brightener additives for nickel electroplating baths.

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A further object is to provide a new and improved process for the preparation of the novel condensation reaction products herein.

An additional object is to provide an improvement in the method for electroplating nickel.

Additional objects and advantages will be readily apparent as the invention is hereinafter described in detail.

In accordance with the present invention, it has now been found that by the addition to the prior nickel electroplating baths of the condensation reaction product of a naphthosultone with an acetylenically unsaturated glycol, nickel electroplating baths are attained which produce extremely bright or brilliant deposits and such is the case even when the nickel deposits are thin deposits.

The naphthosultone herein is the inner anhydride of the corresponding hydroxynaphthalene sulfonic acid. Thus the 1,8-naphthosult0ne is the inner anhydride of l-hydroxynaphthalene-8-sulfonic acid, and the 1,7-naphthosultone is the inner anhydride of 1-hydroxynaphthalene-7-sulfonic acid. The 1,8-naphth0sultone has the formula:

The condensation reaction is carried out with the naphosulfone and acetylenically unsaturated glycol present in at least those amounts required to stoichiometrically react to form the condensation reaction product herein. Usually the naphthosultone and acetylenically-unsaturated glycol are reacted together in equimolar portions to form the condensation reaction product.

The prior nickel plating baths which are improved upon by the present invention contain water as solvent or continuous phase, and a water-soluble compound of nickel, for instance a nickel salt such as the sulfate, sulfamate or fluoborate of nickel. In addition these acid baths usually contain chloride ions to enable anode corrosion, boric acid, a stabilizer for the bath, one or more levelling agents, and one or more depressants of surface tension or wetting agents.

In place of the known levelling agent or agents, the novel condensation reaction product or products of naphthosultones and heterocyclic aromatic compounds containing one or more five-membered heterocyclic rings including at least one ring nitrogen atom and one or more labile hydrogen atoms can be added to the bath as levelling agent. Such levelling agents are disclosed and claimed in copending US. patent application Ser. No. 492,266, entitled, Nickel Electrodepositing Baths and Novel Condensation Reaction Products as Levelling Agents Therefor, filed Oct. 1, 1965.

The condensation reaction product herein has a molecular structure including one or more units of the formula:

4 least 1 and typicaly as high as 100 and even higher. The at least one levelling agent. exact value of corresponds to the molecular weight of the (6) at least one depressant of surface tension, such as particular condensation reaction product obtained at the lauryl sulfate. particular reaction temperature and time of the conden- In addition, in accordance with this invention, the bath sation reaction. 5 comprises at least one bath-compatible condensation reac- When butynediol, e.g. 2-butyne-l,4-diol is the glycol tion product compound of a sultone, for example the naphcondcnsed with the naphthosultone, the product obtained tho-1,8 sultone, with the acetylenically unsaturated has a molecular structure including one or more units of glycol, i.e. the glycol as such, e.g. a butynediol, or a the formula: derivative of the unsaturated glycol and especially the hishydroxyethylether of the butynediol, in a proportion of --S02 0 CH CH preferably from about 0.05 to about 2 g./l.

Such a bath is preferably operated as follows:

1) mechanical agitation of the cathode bar. (2) a temperature of 20-70 C., depending on the concentration of nickel ions and of the desired plating y speed, this temperature being preferably between 55 and wherein has a value as aforesaid.

The condensation reaction of the acetylenic glycol and (3) PH of preferably about 50. the naphthosultone herein is illustrated by the following (4) current density of amps/(1mg, optimally 7 equatlon: amps/dm. for a bath temperature of 65 C.

SO: 0 The novel condensation reaction product herein can be I added to the plating bath either as such or when in solution in an inert, i.e. non-reactive with respect to the con- HO-(CHg)nOECGHiOH stituents of the plating bath, liquid solvent. Exemplary of the inert liquid solvent is water. However any inert liquid solvent which is compatible with the electroplating bath L I can be utilized. The proportions of the condensation re- OCH;)OEC-GH3\O- action product in such additive agent composition can be k j varied over wide limits, and do not form a part of this H 0 invention. It will suffice to point out that with higher smaller quantities of such addition agent composition are y required to be added to the bath to obtain the desired concentration therein of such product, than when lower concentrations of the condensation reaction product are present in the additive agent composition.

The preparation process for preparing the condensation wherein n, n and y have the value aforesaid.

The condensation reaction of the acetylenically-unsaturated glycol, the bis-hydroxyethylether of 2-butyne-1,4- diol, proceeds according to the following reaction:

wherein y has the value aforesaid. reaction products herein comprises, in its broader aspects,

Acetylenically-unsaturated glycols suitable for the conheating a mixture of the naphthosultone and the acetydensation reaction herein include the mono-acetylenically lenically unsaturated glycol to an elevated reaction temunsaturated glycols and especially those having 4-8 inperature below 95 C., and maintaining the mixture at elusive carbon atoms per molecule, for instance the buthe reaction temperature until its viscosity increases aptynediols, e.g. 2-butyne-1,4-diol, 1-butyne-l,4-diol, as well preciably and the mixture becomes of a syrupy consistency, as pentynediols and hexynediols, and derivatives of such which is indicative of the condensation reaction having unsaturated glycols, for instance the bis-hydroxyethylether occurred. The thus-treated mixture is then cooled to amof butynediol which itself is a mono-acetylenically unsatubient temperature, for instance by being permitted to cool rated glycol although containing ether linkages. Exemdown or by indirect heat exchange with a cooling fluid, e.g. plary of the naphthosultones suitable for the condensation cooling water. reaction are 1,8-naphthosultone and 1,7-naphthosultone. More specifically the preparation process involves grad- The naphthosultones herein are prepared by the intraually heating a mixture of the naphthosultone and acetmolecular condensation of the corresponding hydroxyylenically unsaturated glycol, usually in equimolar pornaphthalene sulfonic acid, and the 1,8-naphthosultone is tious, to an elevated temperature below C., preferobtainable in commerce. The acetylenically unsaturated 65 ably of the order of 50 C., to effect dissolution of the glycols, the butynediols, are also obtainable in commerce, naphthosultone in the glycol. The thus-obtained soluas are the bis-hydroxyethylethers of butynediols. tion is then heated to a reaction temperature above 65 Nickel electroplating baths improved upon by the pres- C. but below 95 C., preferably of the order of 80 C., ent invention contain, in addition to water as solvent or and the solution maintained at a reaction temperature continuous phase, the following: within the range stated until the solution becomes of a (1) nickel ions, as sulfate, sulfamate, or fluoborate. syrupy consistency which typically requires about 4 hours (2) chloride ions, to permit anode corrosion. time. The thus-treated mixture is then cooled to room (3) boric acid. temperature. (4) a stabilizer, such as saccharine, paratoluenesulfon- The following examples further illustrate the invention amide, hexamrnine, or cyanuric acid. but are not restrictive thereof. In the examples, the aque= ous nickel plating bath compositions are given with amounts of ingredients being in grams per liter, along with operating conditions:

n and n' are each an integer of 1-2, and y is an integer of value of at least 1. 2. The composition of claim 1 wherein the compound Example NiSOz-7H2O Saceharin Paratoluenesulionami Cyanuric acid Compound A Compound B pH Temperature C.) Current density (a./dm.

w 0000 m who a enowmv-nccoo c: c: ooo a awe Gamomi-HOIQCOO The preparation of Compounds A and B, and more generally, of the condensation reaction product compounds of this invention takes place as follows, by a method which itself comprises part of this invention:

Into a reflux retort, are added in stoichiometric amounts the acetylenically unsaturated glycol, e.g. butynediol or the bis-hydroxyethylether of butynediol, and the naphthosultone, e.g. 1,8-naphthosultone. First, the mixture is gradually heated to about 50 C. thereby dissolving the 1,8-naphthosultone, and then the mixture is heated to about 80 C. and maintained at that temperature for 4 hours; whereby the viscosity increases until the liquid becomes syrupy. The temperature of the mixture is then returned to ambient or room temperature. The solution thus obtained is useable directly as a brightener under the conditions cited above.

Of the above examples, those baths containing Compound A give the better results; in particular, nickel electroplating baths containing Compound A produce nickel deposits which are brighter and better levelled at microns thickness than those produced from baths containing Compound B to microns thickness.

In all examples, baths containing brighteners of this invention produce extremely brilliant deposits even when quite thin.

By comparison, nickel electroplating baths were prepared which were identical to those containing Compound A, but in which the compound was replaced by equivalent quantities of unreacted bis-hydroxyethylether of butynediol and of 1,8-naphthosultone as such (i.e., not subjected to the aforementioned condensation reaction). The nickel deposits obtained from such baths were semibright, cloudy and non-levelled, and were of no commercial importance.

What is claimed is:

1. A composition comprising a solution in an inert liquid solvent of a compound having a molecular structure including at least one unit of the formula:

R and R are selected from the group consisting of oxymethylene and oxyethylene and are the same, m and m are each an integer of 0-1,

has a molecular structure including at least one unit of the formula:

wherein R and R are selected from the group consisting of oxymethylene and oxyethylene and are the same,

m and m are each an integer of 0-1,

n and n are each an integer of 1-2, and

y is an integer of value of at least 1.

3. The composition of claim 2 wherein the compound has a molecular structure including at least one unit of the formula:

Y wherein n and n are each an integer of 1-2, and y is an integer of value of at least 1. 4. The composition of claim 2 wherein the compound has a molecular structure including at least one unit of the formula:

I 0-CH2-CHz-O-CHa-CEC-CHz-O-CHz-CHz-O- wherein y is an integer of value of at least 1.

5. In a method for the electroplating of nickel, the improvement which comprises effecting the electroplating of the nickel from an aqueous acidic nickel electroplating bath containing a source of nickel ions and as a brightener a compound having a molecular structure including at least one unit of the formula;

LSIO

wherein R and R' are selected from the group consisting of oxymethylene and oxyethylene and are the same,

In and m are each an integer of 0-1,

n and n' are each an integer of 1-2, and

y is an integer of value of at least 1. said compound being present in the bath in an amount sufficient to impart brightness to the nickel electroplate.

6. The method of claim wherein the compound has a molecular structure including at least one unit of the formula:

wherein n and n are each an integer of 12, and y is an integer of value of at least 1. 8. The method of claim 6 wherein the compound has a molecular structure including at least one unit of the formula:

it SO: 1

wherein y is an integer of value of at least 1.

9. An aqueous acidic nickel electroplating bath containing a source of nickel ions and as a brightener a compound having a molecular structure including at least one unit of the formula:

wherein R and R are selected from the group consisting of oxymethylene and oxyethylene and are the same, In and m are each an integer of 0-1, n and n are each an integer of 1-2, and y is an integer of value of at least 1,

said compound being present in the bath in an amount sufiicient to impart brightness to the nickel electroplate. 10. The nickel electroplating bath of claim 9 wherein the compound has a molecular structure including at least one unit of the formula:

OCHiC GCHiO- wherein y is an integer of value of at least 1.

11. The aqueous acidic nickel electroplating bath of claim 9 wherein the compound has a molecular structure including at least one unit of the formula:

wherein y is an integer of value of at least 1.

12. An aqueous acidic nickel electroplating bath containing a source of nickel ions and as a brightener a compound having a molecular structure including at least one unit of the formula:

R and R are selected from the group consisting of oxymethylene and oxyethylene and are the same, m and m are each an integer of 0-1, n and n are each an integer of 1-2, and y is an integer of value of at least 1, said compound being present in the bath in an amount sufficient to impart brightness to the nickel electroplate. 13. The electroplating bath of claim 12 wherein the brightener is contained therein in amount of approximately 0.05 to 2 g./l.

, References Cited UNITED STATES PATENTS 5/ 1949 Hoflman 20449 3/1959 Giindcl et a1 20449 JOHN H. MACK, Primary Examiner G. L. KAPLAN, Assistant Examiner U.S. Cl. X.R.

P0405" UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Pat 1,167,146 Dated Tuly 22 mm Inventor(s) Jean 1, 91,118 LQXQSSGUI It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

F- Column 1, line 36, after "products" and before "as", the I comma should be deleted. Column 2, 1ine 28, "sulfone" should read sultone olumn 5, line 23, that portion of the formula reading "Z-butylenel, 4-" should read Z-butyne-l, 4- line 48, "to" should be --at--.

Col n 6, line 50, that portion of the formula reading @ij should read as Column 7, line 5, that portion of the formula reading "-C;0-" should read -C=C- line 37 that portion of formula reading should read SIG NED fiND SEALED APR281970 6 Attest:

Edward M. Fl t mscmnu r. 'SGHUYLER, m- Atbesting Officer Commissioner of Patents 

